There is known an ID card (Identity card) print process for printing an ID card the two sides of which are printed with image data. In the ID card print process, an image reading unit reads the image data printed on the surface of an ID card, then the operator turns the ID card over to read the image data printed on the back-side of the ID using the image reading unit. Then, the image data is arranged in a storage unit in such a manner that the image data is input to the surface of a sheet, and an image forming process is carried out using an image forming unit.
However, to the moment an ID card is printed, this ID card print process takes a great amount of time as the image data stored in the storage unit needs to be arranged and an image forming process needs to be carried out by the image forming unit after the image data printed on the surface and the back-side of the ID card is read by the image reading unit. Moreover, in this ID card print process mode, when the read image data is stored and arranged in the storage unit the read image data is compressed or decompressed until the image data read in another print process mode in the same way is printed, which leads to a poor performance.